I use just-ping.com when I need to ping my servers from various locations in the world to see if it’s working right. I have noticed that when CSF Firewall is installed and active I get losts of lost packets when trying to ping the server, but when I disable it – results are okay. The solution for this is to increase the ICMP_IN_RATE value from 1/s to 30/s.

To do so login to your WHM go to ConfigServer Security & Firewall and there click on Firewall Configuration button and on that page locate ICMP_IN_RATE (CTRL+F can help you locate it) and then increase it’s value from 1/s to 30/s. Scroll all the way down and pres “Change” button to save the changes. Restart the firewall and test it again.

04.12.2014 Update: Looks like the just-ping (now on new address cloudmonitor.ca.com) changed the way their service works. Now they ping you instantly from all places at once and CSF firewall will block most of these out and you’ll get lost packets in report. So for the testing you should set ICMP_IN_RATE to 0 – that will disable it – and then you can do tests. Other way around it to set it to fairly large number (200 or even bigger). Don’t forget to restart CSF + LFD in order these changes to apply.